is specified for an element, any padding or border of the element is drawn inside the specified width and height, "as commonly implemented by legacy HTML user agents". Internet Explorer 8, WebKit browsers such as Apple Safari 5.1+ and Google Chrome, Gecko-based browsers such as Mozilla Firefox 29.0 and later, Opera 7.0 and later, and Konqueror 3.3.2 and later support the CSS3 box-sizing property. Gecko browsers previous than 29.0 support the same functionality using the browser-specific -moz-box-sizing property. border-box is the default box model used in Bootstrap framework. References External links The world wide web consortium (W3C) specification of the box model A tutorial on the CSS box model Tantek Çelik's description of the "box model hack" Getting Internet Explorer to Play Well with CSS - article on about.com that outlines various ways to get around box model problem and other IE bugs. Cascading Style Sheet Compatibility in Internet Explorer 7 - MSDN article, July 2006. CSS Box Model differences in Firefox and Internet Explorer - Further explanation of the rendering differences between Mozilla Firefox and Internet Explorer. Web development CSS frameworks Cascading Style Sheets